Generally, rearview mirror devices for rearward recognition are attached to the right and left door of a vehicle. However with this rearview mirror device, the road surface ranging from downward to a slantingly forward cannot be visually recognized. For this reason, especially in the field of view seen from a driver's seat of a car, the road surface near the front wheel on the side of a passenger seat serves as a dead angle. When an obstacle exists near this field, there is a possibility of involving this in a front wheel without knowing. Then, in order to avoid such a situation, a camera built-in type rearview mirror device including a camera module capable of visually recognizing the road surface near a front wheel, and its illumination light source is developed variously. (JP-A-2000-115759, U.S. Pat. No. 5,497,306).
In this kind of camera built-in type rearview mirror device, the above-described camera module consists of a camera main body part which includes picture sensors such as lens or CCD (Charge Coupled Device), and picture signal-processing part, and a power supply part, in such a way that the road surface near the front wheel is displayed in a picture on the monitor by outputting the picture signal from a picture signal-processing part to the monitor of the vehicle compartment. And the opening part for the lens of the camera main body part and illumination light source to be faced is formed in a mirror housing where such a camera module is built in. Usually, the opening part is closed by a transparent cover.
By the way, in the aforementioned conventional camera built-in type rearview mirror device, the area of the opening part where the lens and illumination light source of the camera main body part are faced is comparatively large. Therefore, the problem that the rigidity of the mirror housing falls, resulting in trembling vibration that is occurred to the mirror, is pointed out. Moreover, since the position of the lens of the camera main body part is restricted by the transparent cover that closes the opening, the problem that photographing feasible viewing angle is generally narrow, is also pointed out.
Furthermore, since protection against dust and moisture impervious methods are not taken inside of the transparent cover, dirt which invaded in the mirror housing from the circumference of the mirror, etc may adhere to the inside of the transparent cover. In addition, fogging and dew condensation may occur in the inside of the transparent cover due to the rise of the humidity in the mirror housing or the fall of temperature, with the result that the translucency of the transparent cover may fall. Furthermore, the illumination light from an illumination light source may turn in to the lens of the camera main body part. Moreover, when water droplet adheres to the external surface of the transparent cover at the time of rainy weather or after car washing or the like, the incidence light onto the camera main body part may be improperly refracted by the lens action of the water droplet. In such a case, it becomes impossible for the camera main body part to photo a clear picture through a transparent cover.
Furthermore, at least a camera main body part of a camera module is formed integrally with a picture signal-processing part, therefore it is necessary to secure a big accommodation space in the mirror housing. However, in a motor-driven containing type mirror housing equipped with an electric mirror, a mirror surface adjusting actuator and a motor-driven containing unit are arranged therein, to thereby make a difficult situation to secure a big accommodation space, with the result that built-in of a camera module may be hard to achieve.